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To drive off uphill on a road with snow

To drive off uphill on a road with snow

Submitted by silvio.k on Thu, 2012-10-25 06:49

Hi

I live in Switzerland. Sometimes in winter I have to drive off uphill
with snow on the road. My father owns a Lexus with rear wheel drive and
often has problems in winter. I own currently an Audi with front wheel drive
and never had any problems in winter.

I'm really interested in the Tesla Model S, but I'm not sure if the
rear wheel drive has problems too in winter.

Bye

Theresa |
25 ottobre 2012

The reason for this difference is due to weight distribution. On ICE vehicles the majority of the weight is in the front which is why front wheel drive cars do better than rear wheel drive. But the Model S does not have this disadvantage and has its weight spread evenly. My assumption is that it will be nearly as good as a front wheel drive vehicle and will definitely be safer in a skid situation as the front wheels will not be trying to slow you down and possibly losing traction.

Dennis |
25 ottobre 2012

the combination of low center of gravity and traction control should allay your fears. here's a nice video of a former roadster and current model s owner driving after a big snow storm in boston. the rear wheel drive was a little concerning for me as well. but, after looking into it, i don't have any concerns.

No big problem with snow but if you stay stuck in snow you must leave the car there until snow melt (no tow hook) or probably void your warranty.

jjaeger |
25 ottobre 2012

No won't void the warranty - rangers can service the stranded vehicle in the snow and you can retrieve in the spring with all being well. Gotta love those rangers...

bgoodwin |
27 ottobre 2012

That was me in Boston with that video. Indeed the Roadster did really well in the snow. I have zero concerns with the Model S in the snow.
I took the Roadster up my hill when I saw another truck stuck spinning their wheels. The road had glazed over. I had no troubles getting up the hill.

Superliner |
27 ottobre 2012

I learned to drive and have "always" driven rear wheel drive cars. Winter driving?? Not an issue when you remember to keep your brain engaged. And in the slickest of conditions such as Ice it does not matter which or how many wheels are driving. The proof will be in the median strips and ditches of America this winter. Think not? just count the front drive cars in the ditch or otherwise stuck this winter lol!!

Timo |
29 ottobre 2012

Four wheel drive is obviously the best solution to icy conditions, but Model S rear wheel drive with that low CoG should make it quite good winter car. Moreover drive setup is like 5% compared to the tires used. Good tires make any car good winter car and bad tires makes them bad. Pay attention to tires you choose and their condition after.

Reason why four wheels is best is simply the fact that four wheels allows less force / wheel to get same outcome, thus lessening slip. Also if one tire gets stuck (or is slipping) you have three instead of one to get loose from that stuck.

OTOH, with four wheels when you lose control you really lose it. That means you find yourself much deeper into ditch than you would with any of the two wheel drive options.

Brian H |
29 ottobre 2012

Traction Control is just as big a factor. Most winter driving stupidity and accidents I've seen involve over-driving the drive tires, and making ice out of snow on the go. People not used to winter driving can't seem to get the idea that more gas/pedal = less traction, and less pedal = more traction.

mrspaghetti |
29 ottobre 2012

@Superliner, Timo

Reminds me of a friend who purposely went off road into an area no vehicle should go thinking he was invincible with 4WD. He wasn't :)

EdG |
29 ottobre 2012

If you go into a snow bank, and the battery pack is sitting on a solid pack of snow, will the temperature control system for the battery pack tend to melt the surface of the snow (through the aluminum casing) and tend to help the car slide downhill (the battery pack is flat)?

Might be good if you just need to get back onto the road from a large snow bank. All you'd have to do is clear the wheels a bit.

On the other hand, if the road is falling off to the side....

Either way, it would be good to know what to expect.

DTsea |
29 ottobre 2012

I'm not going to risk my new Model S in the snow where I live (Seattle). It's very hilly, no roads are ever plowed because snow is only once a year, and most other drivers are very inexperienced and drive dangerously. I'll just drive my wife's Volvo to work those days!

Timo |
30 ottobre 2012

"other drivers are very inexperienced and drive dangerously"

It shouldn't be funny, but somehow it is: in here we have snow and ice every year sooner or later in October and sometimes as early as late September. This is to be expected, but somehow every god d*mn year at first ice we have a pileup. Somehow that ice manages to surprise those "other drivers" every year.

I too would be reluctant to take my new car onto road at first snow. Later when those other drivers are already repairing their cars it would be relatively safe to drive it.

Brian H |
30 ottobre 2012

Yes; wait for the first big wave of ijits to take themselves out of circulation! Good plan.

Theresa |
30 ottobre 2012

Yes there are people who don't recall how to slow down with the first snowfall but what many don't realize is the first snow of the season is actually much more slippery than later snowfalls due to the warmer temps and warm roads that haven't been cooled from exposure to cold temps for a long period of time. Just take a handful of snow in your hands and see how much friction there is when you first pick it up to when it starts to melt in your hand and you get the idea. Since it is closer to melting it forms ice with water on it quickly from warm tires.

DTsea |
30 ottobre 2012

In Seattle we only get the 'first snow.' Even if it snows again it's usually been warm in between.

Teoatawki |
30 ottobre 2012

It's astonishing how short peoples' memories are. Back in nw Ohio, I saw it every year. First snow, ijits ahoy! Plenty of fender benders, and a few in ditches. Then first ice: repeat with more serious accidents, multicar pileups, cars wrapped around poles, etc.

Now in Seattle area, it's déjà vu: except when the first fall rain happens, it's almost like they haven't seen rain before. Then snow or ice -- disaster.

tharasix |
31 ottobre 2012

Same with Minnesota. You'd think of any state in the 48 contiguous, Minnesotans would take the first snowfall seriously, but no.

FWD + Winter Tires = Good, not great. (unplowed hills can be a problem if your traction control is too aggressive)

RWD + Winter Tires = Acceptable. (you can drive with some confidence but stress is still high because you may plow straight ahead over the next turn)

UPSHOT: Drivetrain is secondary. Good winter tires are non-negotiable.

Dave-LasVegas |
9 novembre 2012

Next year's "Model X" is an all-wheel drive variant on the Model S; perhaps it would better meet your concerns. I'll bet it can power up your favorite alp all day long.

Brian H |
9 novembre 2012

Dave;
The Perf version of Model X only.

jerry3 |
10 novembre 2012

Mayhemm,

Vehicle Stability Control minimizes the difference between all three drivetrain choices. Studless winter tires from a tier one tire manufacturer are very important.

Brian H |
10 novembre 2012

jerry3;
Does SC and/or TC deal with the "plowing straight ahead over the next turn" issue?

My own one non-winter 'free-sliding' experience occurred with a FWD Civic in the mountains. Came to a left turn, facing a steep drop-off, and the road was lubricated with small gravel. The car started to straight-line. My cerebellum took over, and I went off the gas, then "blipped" front wheels to get back in contact with the pavement. That sweet little car jerked me around the corner, back in control.

Like they say in combat, there's nothing like getting shot at -- and missed!
;)

jerry3 |
10 novembre 2012

Brian,

Yes, Stability control deals with that. Very well in fact. Traction control does not deal with that at all, it's about tire spin. They are really two separate systems.

I have it in the Prius and it's almost impossible to make it misbehave. Even if you get it totally sideways (meaning that you're driving like a complete idiot, or are just trying to test the limits) it corrects itself (regardless of whether it's sideways because of plowing straight or sideways because of rear end overtaking the front end).

From the manual:

The followings are two examples that can be considered as circumstances in which the tires exceed their lateral grip limit. The Enhanced VSC system is designed to help control the vehicle behavior by controlling the motive force and the brakes at each wheel when the vehicle is under one of the conditions indicated below.

To determine the condition of the vehicle, sensors detect the steering angle, vehicle speed, vehicle’s yaw rate, and the vehicle’s lateral acceleration, which are then calculated by the skid control ECU.

1) Determining Front Wheel Skid

Whether or not the vehicle is in the state of front wheel skid is determined by the difference between the target yaw rate and the vehicle’s actual yaw rate.

When the vehicle’s actual yaw rate is smaller than the yaw rate (a target yaw rate that is determined by the vehicle speed and steering angle) that should be rightfully generated when the driver operates the steering wheel, it means the vehicle is making a turn at a greater angle than the locus of travel.

Thus, the skid control ECU determines that there is a large tendency to front wheel skid.

2) Determining Rear Wheel Skid

Whether or not the vehicle is in the state of rear wheel skid is determined by the values of the vehicle’s slip angle and the vehicle’s slip angular velocity (time-dependent changes in the vehicle’s slip angle). When the vehicle’s slip angle is large, and the slip angular velocity is also large, the skid control ECU determines that the vehicle has a large rear wheel skid tendency.

When the skid control ECU determines that the vehicle exhibits a tendency to front wheel skid or rear wheel skid, it decreases the engine output and applies the brake of a front or rear wheel to control the vehicle’s yaw moment. The basic operation of the Enhanced VSC is described below. However, the control method differs depending on the vehicle’s characteristics and driving conditions.

1) Dampening a Front Wheel Skid

When the skid control ECU determines that there is a large front wheel skid tendency, it counteracts in accordance with the extent of that tendency. The skid control ECU controls the motive power output and applies the brakes of the front wheel of the outer circle in the turns and rear wheels in order to restrain the front wheel skid tendency.

2) Dampening a Rear Wheel Skid

When the skid control ECU determines that there is a large rear wheel skid tendency, it counteracts in accordance with the extent of that tendency. It applies the brakes of the front wheel of the outer circle of the turn, and generates an outward moment of inertia in the vehicle, in order to restrain the rear wheel skid tendency. Along with the reduction in the vehicle speed caused by the braking force, the excellent vehicle’s stability is ensured.

In some cases, the skid control ECU applies the brake of the rear wheels, as necessary.

There's more and some diagrams, but this should give you the general idea.

Brian H |
11 novembre 2012

Wondering about that specific situation I described, where the fronts are suddenly on ball-bearings (and of course were the driving wheels!). Would SC have duplicated my maneuver? Or interfered with it?

jerry3 |
11 novembre 2012

Duplicated it but much faster than you could have done. What you're describing is "When the front wheels lose grip in relation to the rear wheels (front wheel skid tendency)."

Brian H |
11 novembre 2012

Good to know! But the downside to all this safety stuff, of course, is the homo sap need to push the limits. I think it's been observed that people quickly take them for granted, and then try to make it exciting anyway. Which means leaving the possibility of gruesome death on the table ...

jerry3 |
11 novembre 2012

Brian,

In this universe there is a race between the engineers trying to create idiot-proof safety systems and the universe creating bigger idiots. So far the universe is winning.

Ironic, since IMO legislators are some of the best examples of idiots.

rmitchum |
12 novembre 2012

@ tesla.mrspaghet...
Hee Hee! Exactly what I was trying to say without actually saying it :-)

Brian H |
12 novembre 2012

Then they're the perfect insider experts in idiot-proofing, no? "What would make the world safe from and for me?"

;D

frode.haugen |
7 marzo 2013

Questions about Tesla S:

Situation 1:
You have stopped in a steep hill, foot on the breake. What happends if you just remove your foot from the break pedal?
Will the car start rolling backwards?
Do you need to push down the accellerator pedal to avoid going backwards?

Situation 2:

Driving up a steep hill. Reducing speed to 0 and not breaking. Same thing, will the car start rolling backwards?

PaceyWhitter |
7 marzo 2013

@ fh

This is actually a user selectable option. There is an option called "creep" which has the MS creep slowly forward if the break has been released (similar to an automatic ICE) if this is selected the MS should hold or move forward if the break is released.

If creep is not selected the MS will roll backward in that situation (similar to a manual ICE)

Some in the forums have suggested a hill hold option that would prevent the rolling back on a hill but not have the car roll forward however Tesla has not implemented this option (they could through a software update in the future)

MandL |
7 marzo 2013

Depends on how steep the hill is. Creep won't keep the Model S from rolling on anything but a fairly slight grade.

Vawlkus |
7 marzo 2013

Creep was really intended for flat to slight inclines. Hill hold is the feature your after, and while its on the list, it hasn't been implemented yet.

Captain_Zap |
7 marzo 2013

On steep hills it is similar to driving a car with a manual transmission even with the "Creep Mode" update. The backwards roll just is not as aggressive as it would be with a manual transmission. With "Creep" off it feels just like a manual transmission when starting out on a steep hill.

To accommodate stops on very steep hills I use the foot brake as I would have used the hand brake in a manual transmission car. Sometimes the car will beep at you briefly but it gets over it.

"Hill Hold" feature is hopefully coming with a firmware update just as the "Creep Mode" was added. That should make it feel more like a traditional automatic transmission but with the added advantage of no gear changes potentially breaking you loose on slippery surfaces. I don't need the "Hill Hold" it since I am accustomed to manual transmissions but I can see other drivers finding it very desirable.

Also, if it is really slippery I will set the regen to low to keep the tires from breaking loose on deceleration while going down some hills. I never had it break loose. I am simply choosing to use the same level of care as I would with any other car.

Captain_Zap |
7 marzo 2013

P.S. The Model S is far superior in the snow to my RWD BMW due to the weight distribution, and transmission issues. I couldn't get my BMW out of my neighborhood with any snow or ice on the road.

Now you have me longing for a visit to Switzerland. I love it there.

torst1 |
8 marzo 2013

Too tired to read the whole thread so I it might have been answered already.
Here it goes.

Advocates for front wheel drive seems to forget that going uphill it is actually a better for å rear wheel drive car. Think of weight distribution.
On a flat tarmac the weight of the petrol engine is transferred straight to the wheels. As the angle of the hill increases the weight will be pushed towards the rear and will put down force on the rear wheels, and thereby giving better traction.

That is why it is recommended to actually turn a front wheel drive car 180 degrees before backing up steep hills in severe winter conditions.

For Tesla S this will mean the weight of the engine already across the drive wheels, and all of that weight will put down force and traction on tires going uphill. I dont think you will have any problems.

chrismcadams1 |
9 dicembre 2013

I own a model s p85+. I live in Chicago. So let me preface this by saying I love my car. However, last night I tried driving a 30 trip on I-290 from downtown chicago to Naperville il. It was the first real snow we have seen, and as such I was interested to see how the car performed. Before heading out too far I realized I had a MAJOR loss of control of the car. I loaded 200 ibs of sand evenly distributed over each of the rear wheels in the trunk and started the trip. I have driving experience in this weather for 14 years. I'm familiar with rear wheel drive vehicles, (my other car is a jaguar xfsupercharged). It was the most frustrating, dangerous, uncomfortable two and a half hour trip to go 30 miles I've ever experienced. Less than 3 " of accumulation and the tires, even with the "traction control" we're useless. We could not control the car over 25mph. There were other real wheel drive vehicles traveling at 55 mph-65mph. On hills the tires would just spin, even with the slightest application of acceleration. We got stuck multiple times. This is on the tollway! A police officer actually pulled us over, asked if we were ok and followed behind us up a hill as I exited the car and had to push the car down and to the sides to get enough traction on a slight hill to get through it. The tires were all replaced 4500 miles ago. I realize Michelin pilots are not winter tires but this was REDICULOUS. We were in the far right lane and every attempt to change lanes, which was only accomplished at 12-15 mph was difficult. Merging traffic on the tollway at that speed was incredibly dangerous, but necessary only to follow the correct roads to get back home. We had MULTIPLE fish tails which I calmly steered out of but lost control even at 15-20 mph. Prior to purchasing the car I was very careful to ask about the experience in snow. I was shown no documentation, but was reassured profusely that the vehicle was tested in snowy adverse weather conditions. Farthest thing from the truth. I'll be bringing my car into the service station in Chicago today looking for an explanation. Has anyone else experienced anything like this?

Bighorn |
9 dicembre 2013

@chris
Explained wholly by your use of summer tires, would be my guess. What was the temp?

Panoz |
9 dicembre 2013

@Chris - wow, that experience is opposite of most posts on this site and I'm HIGHLY interested in what the final answer is (car problem or tire problem or both).

Earl and Nagin ... |
9 dicembre 2013

hmm, I wonder if the extra 200 lbs of sand in the rear threw off the traction control?
I haven't been in snow much but I have driven the MS on ice and it is very sure-footed - even without snow tires.

PJDoty |
9 dicembre 2013

This has not been my experience. Was traction control somehow disabled?

Theresa |
9 dicembre 2013

I live in Iowa and we had 4 inches of snow here. I put on the tirerack dunlop special 19 inch wheel/tire combo and I had absolutely no issue whatsoever. In fact I could accelerate in places I was expecting to spin out. At most stops I was able to take off like normal and leave all the other cars far behind me. My guess is it is your tires. Winter tires really do make a difference.

Last winter I left on the 21 inch tires that came with the car and had much more trouble getting around although even then I was able to get around way better than you have described.

Theresa |
9 dicembre 2013

Also I cannot get the wheels to spin unless I am accelerating around a corner. It really does sound like you may have had the traction control turned off.

JonathanL |
9 dicembre 2013

Chris,

I have experienced the same thing with Michelin Pilot Sports, but it was on my real wheel drive Porsche. Those tires have no business being anywhere near snow. They are useless and dangerous in such conditions.

I have the Continental Extremes and I assumed they would be as bad as the Pilots Sports in snow so I got the 21" Pirelli snows from Tire Rack and had my SC install them last week. We had about an inch of snow here in NJ last night and I took the car for its first spin in the snow and I was impressed. I was mashing the goose pedal and but for the TC light flashing, I could hardly sense any spin. The car went exactly where I wanted it to. Did much better than my BMW550 with all seasons ever did. Even my X5 with all seasons would have been less stable in such conditions. I really need to go into heavier snow before I can make final judgement, but so far so good.

My advice would be to put the slicks in the garage and get some snows. At a minimum it will save you some inside wear on your rear Pilot Sports.

Jonathan

Andercam |
9 dicembre 2013

Summer tires shouldn't be driven when the temps are below 45 degrees, as they will have reduced traction. No way in hell should they be driven in the snow... that's suicide!
I purchased some aftermarket 20" wheel's and put Continental DWS tires on my "S", and haven't had any issues in the snow and/or below zero temps we've had lately.